A previously known sealing device of this kind comprises an elastic material sealing ring consisting of a main body sealingly and unrotatably connected with one of the machine elements and a sealing lip unitary with the main body and contacting a counterface nonrotatably supported by the other machine element, the sealing lip sliding against said counterface when the machine elements are rotated in relation to each other.
In a common type of sealing device of the above kind, the sealing ring consists of a substantially cylindrical, tubular main body to which the sealing lip is connected at the inner periphery of one of the side surfaces of the main body, forming a V-shaped groove between the main body and the sealing lip.
In a previously known sealing device of this kind, it is known to mount the sealing ring on a cylindrical surface, for example a shaft, and to lock the sealing ring in relation to said counterface by means of the elastic main body. Prior to the mounting of the sealing ring on the cylindrical surface, the main body has an inner diameter which is substantially smaller than the outer diameter of the cylindrical surface, so that the main body of the sealing ring will be in a tensioned condition on the cylindrical surface when the ring has been mounted thereon. The lip of the sealing ring has a predetermined axial compression in relation to the counterface providing a relatively small lip pressure against the counterface.
When using sealing devices of the aforementioned kind in the region of the bearing arrangement for two machine elements which are rotatable in relation to each other, for example in a washing machine, the sealing device has the object of preventing introduction of, for example, a solution of water, detergent and textile fibers to the bearing due to the grip of the main body of the sealing ring on the cylindrical surface on which the sealing ring is mounted, the sliding and frictional contact between the lip and the counterface, and the static seal between the counteface and the housing in which the bearing is arranged. Partly due to the introduction of fluid detergents which may have a swelling effect on the elastic material of the sealing ring, and partly due to oxidation of the surface (e.g., of aluminum) on which the sealing ring is mounted, it has become common practice to arrange the main body of the sealing ring in an annular groove in the first machine element. By taking this precaution, the problems caused by swelling and oxidation have been eliminated. However, the positioning of the main body of the sealing ring in a groove leads to some manufacturing problems due to more stringent tolerance requirements and mounting problems because of the air entrapped in the annular groove when the sealing ring is being mounted therein.